There are other consensus algorithms that have been used in several other permissionless blockchains to remove the disadvantages posed by PoW and PoS. For example, Proof of Retrievability (PoR) [1]} consensus algorithm. It is also referred to as Proof of Space. Instead of computational resources requirements like PoW, here, a user's chances of block formation are in proportion with the amount of local space available committed to the network as stake. It is used in Permacoin cryptocurrency blockchain [2]}. A consensus protocol called Ripple [3]} is used in XRP cryptocurrency. However, in Ripple, the validating nodes and client nodes are predefined. Each validator has a list of trusted validators known as unique node list (UNL). The validating votes are collected for each transaction from the UNL peers before inducting them into the block. Further, at least \(80\%\)  yes votes are required for the transactions to go through validation.
